In arithmetic processing devices, memory access is carried out based on atomic instructions that execute a plurality of processes in an indivisible manner. Atomic instructions refer to instructions that guarantee the obtaining of results that are the same as when a plurality of processes have been executed in a predetermined order. In the execution of atomic instructions, target data is protected by locking-target addresses being registered and locked in a lock register.
Related technology is disclosed in Japanese Laid-open Patent Publication No. 4-65736.